Improvement in door-alarms



F. G. RENNER. Door-Alarm.

No. 206,899. Patented Aug. 13.1878.

N.PEIER$, PHOTO-LITHOGRAPHER. WASHINGTON, D c.

UNITED STATES PATENT OFFICE.

FRANCIS G. RENNER, OF NEW MID WAY, MARYLAND.

IMPROVEMENT IN DOOR-ALARMS.

Specification forming part of Letters Patent N0. 206,899, dated August13, 1878; application tiled July 18, 1878.

To all whom it may concern:

Be it known that I, FRANCIS G. RENNER, of New Midway, Frederick county,State of Maryland, have invented anew and Improved Door-Alarm; and Ihereby declare the following to be a full, clear, and exact descriptionof the same, reference being had to the accompanying drawings, makingpart of this specification, in which- Figure 1 is a perspective view ofthe apparatus applied to a door. Fig. 2 is a front elevation, with thegong and easing removed. Fig. 3 is a side elevation, showing theattachment of the yoke to the knob. Fig. 4 is a view of the strikingapparatus, with the hammer retracting, so as not to strike the bell whenthe knob is drawn.

The object of my invention is to provide an alarm adapted to be attachedto open-faced locks, whereby the turning of the knob will strike analarm indicative of the turning, and provided with a detent or stop,whereby the striking of an alarm may be dispensed with, when desired,without removing the apparatus from the door; and it consists in ametallic yoke screwed to the shank of the knob by means of a screw,which holds the shank of the spindle, having attached to each end ofsaid yoke parallel chains or links, having their other ends attached toa spreader, whose ends, in turn, are attached to a loop, which operatesthe latch to throw a hammer, striking the gong.

It further consists in a sliding bar provided .with certain stops as adetent to hold the striking-hammer out of contact with the gong when itis desired to prevent the alarm from ringing.

In order that those skilled in the art may make and use my invention, Iwill proceed to describe the manner in which I have carried it out.

In the drawings, A is a door, to which is attached the lock B, providedwith an ordinary latch-knob, 0, having a shank, 1). Around this shank I)fits a sheet-metal yoke, E, provided with a hole, through which passesthe screw F, that holds the shank to the spindle. From each end of theshank pass links or chains G G, having their other ends attached to eyesa a in a bow, H. The bow H has on its ends eyes b b, which engage ineyes (I d of the loop (1, which runs through an eye, 0, in the barf,pivoted. at g to a latch-shaped lever, t. Secured to the door by screws8 s is a plate, I, to which is journaled the operating parts of thealarm mechanism. The latch-shaped lever is pivoted at j, and hasattached to its lower end a coiled spring, k, and rests against a pin,I, which limits its movement. The upper end is cam-shaped for purposeshereinafter described. an is a hammer for striking the gong, and isprovided with a striking-lever, n, pivoted at o, and is provided with atriangular-shaped head, 1), lying contiguous to the cam-shaped end oflever 1'. Above the pivot 0 there is attached to lever n a coiledspring, 1, fastened to a pin, q, which also holds the end of spring 7..Lisa coiled spring attached to plate I, having a projecting arm whichbears against the hammer-lever n, to afiord an elastic bearing toretract the hammer from the gong after the blow is struck. In a guide,t, slides a rod, P, provided with a U-shaped bend, t, which acts as adetent to hold the hammer away from the gong and disengage thetriangular-shaped head 12 when it is do sired to use the knob freelywithout striking an alarm. This disengagement is effected by means of ahooked end, 0?, catching the hammer-lever, and drawing it toward thecenter of the gong, where it is retained by turning the U-shapedprojection behind the pin q.

It will be observed that by the use of the yoke, attached by means ofthe screw that holds the shank to the spindle, the bearingpoints of thelinks of the chains are thrown outward, so as to avoid rubbing againstthe corners of the face of the lock, and the use of the bow to keep thechain or links parallel keeps the key-hole freely exposed.

The alternate raising and lowering of latchlever 15 by means of therotation of the knob throws the cam-shaped end against thetriangular-shaped head forcing it outward, and stretching the spring 1"until the cam-shaped head passes beneath the triangular-shaped head, andthe retraction of the spring strikes a blow on the gong. This operationextends spring 1., and when the knob is released the retraction ofspring k against the lower side of the triangular-shaped head 19 againforces it back; and it strikes another blow on the p and spring 1', andgon Q, all constructed,

0 return. arranged, and operated as described.

Having thus described my invention, what I 2. The sliding rod P,provided with a bent claim as new, and desire to secure by Letend a',and U-shaped bend t, in combination ters Patent, iswith thehammer-levern and pin q, as de- 1. The yoke E, shank-screw F, shank D,scribed.

parallel links G G, bow II, provided with FRANCIS C. RENNER. eyes a a bb, and pivoted barf, in combination Witnesses: with the lever 1',provided with spring I; and R. K. EVANS,

pin I, and hammerlever 11, provided with head B. ZEVELY.

